Apparatus for manufacturing a quantum-dot element

ABSTRACT

An apparatus for manufacturing a quantum-dot element is disclosed. The apparatus includes a reaction chamber for evaporating or sputtering at least one electrode layer or at least one buffer layer on the substrate. The substrate-supporting base is located inside the reaction chamber for fixing the substrate. The atomizer has a gas inlet and a sample inlet. More specifically, the gas inlet and the sample inlet feed the atomizer respectively with a gas and a precursor solution having a plurality of functionalized quantum dots, and thereby form a quantum-dot layer on the substrate. The apparatus of the present invention can form a quantum dot layer with uniformly distributed quantum dots and integrate the processes for forming a quantum-dot layer, a buffer layer, and an electrode layer together at the same chamber. Therefore, the quality of produced element can be substantially improved.

BACKGROUND OF INVENTION

1. Field of Invention

The present invention relates to an apparatus for manufacturing aquantum-dot element and, more particularly, to an apparatus formanufacturing a photoelectric element with colloidal quantum dots.

2. Description of Related Art

Recently, the hybrid of organic or inorganic materials has become theemphasis of the development in photoelectric materials. On the otherhand, the nano-particulate obtained by liquid or gaseous synthesis isalso the focus of the development in material technology. Although thenano-particulate as well as the composite of the nano-particulate andthe organic molecule inherently have good material property, they becomedeteriorated when being applied to the photoelectric devices. The mainproblem lies in that the manufacturing process of the nano-particulateis not compatible with the vacuum process for manufacturing thephotoelectric element and, therefore, the manufacturing of thephotoelectric element with the nano-particulates can not be carried outin a continuous process.

Generally, the quantum dot of the quantum-dot element is formed byeither a vacuum process or chemical synthesis. The vacuum processfurther includes the Molecular Beam Epitaxy (MBE) method, the ChemicalVapor Deposition (CVD) method, and the Ultrahigh Vacuum Physical VaporDeposition (UHVPVD) method. However, the quantum dots formed by thesevacuum processes usually have too large particle sizes (usually largerthan 10 nm) and too low densities. Also, the particle sizes are notuniform enough. Therefore, the quantum dots formed by the vacuum processare unsuitable for manufacturing device with large superficial contentAs for the chemical synthesis, it can produce quantum dots withwell-distributed size, which generally ranges from 1 nm to 10 nm. Inaddition, the quantum dots formed by the chemical synthesis have ahigher density, so they can be used to manufacture devices with largesuperficial content. The quantum-dot layer formed by the conventionalchemical synthesis is shown as FIGS. 1 a to 1 c. First, the particles 10and the organic molecules 20 are mixed in an atmosphere of inert gas,which prevents the particles 10 from oxidizing. Namely, the quantum dotsare dispersed in the organic solvent, as shown in FIG. 1 a. Afterwards,the quantum dots in the organic solvent are deposited onto the substrate30 by spin coating in the grove box, as shown in FIG. 1 b. Subsequently,the substrate 30 is put into the vacuum evaporation chamber or thesputtering chamber for depositing a carrier transport film or anelectrode 40, as shown in FIG. 1 c. However, the quantum dots may easilyaggregate in the aforesaid process, as shown in FIG. 2 c. Besides, theproduct is easily contaminated during the mixing or the spin coatingstep, and consequently suffers from quality deterioration. Moreover, theproduct might be damaged when it is transported between differentmanufacturing apparatuses. In addition to the above-mentioned method,the quantum dots may also be adsorbed onto the substrate by dipping.However, although a uniform layer of quantum dots can be formed, thesolvent might easily contaminate other parts of the quantum-dot elementsuch as the carrier transport layer or the electrode.

In order to overcome the imperfection of such a non-continuous process,the apparatus for manufacturing a quantum-dot element of the presentinvention combines the conventional aerosol spraying process with thevacuum process. In particular, the aerosol spraying process is used forintroducing the solid powders. Therefore, the organic-inorganiccomposite element can be manufactured in a single chamber, and thebottleneck of deterioration in material quality can be substantiallyimproved.

SUMMARY OF THE INVENTION

The object of the present invention is to provide an apparatus formanufacturing a quantum-dot element so that the electrode layer, theemitting material layer, and the carrier transport layer of thequantum-dot element can all be formed in the same apparatus, and thusthe quality loss due to transferring between different apparatuses canbe substantially avoided. Furthermore, the quantum dots can bedistributed uniformly, the sizes of quantum dots can lie in thenano-order, and the performance of the quantum-dot element in light,electricity, and magnetism can be improved.

In order to achieve the above object, the apparatus for manufacturing aquantum-dot element having a quantum-dot layer formed on a substrate,comprises a reaction chamber, a substrate-supporting base, and anatomizer. The reaction chamber provides a reaction condition forevaporating or sputtering at least one electrode layer or at least onebuffer layer on the substrate. The substrate-supporting base is locatedinside the reaction chamber for fixing the substrate. The atomizer has agas inlet and a sample inlet. Moreover, the sample inlet feeds theatomizer with a precursor solution having a plurality of functionalizedquantum dots, and thereby forms a quantum-dot layer on the substrate.

The apparatus for manufacturing a quantum-dot element of the presentinvention can produce devices having the functionalized quantum dots,for example, a light-emitting diode, a laser diode, a detective devicesuch as a light sensor or chemical sensor, photonic crystals, lightmodulators, magnetic thin film, or a battery using solar energy.

Generally, the quantum-dot element is constructed of a bottom electrodelayer, a buffer layer, a quantum-dot layer, another buffer layer, and atop electrode layer formed on a substrate. The buffer layer is usuallycomposed of at least one carrier injection/exportation layer pair, andcan also be omitted optionally. Furthermore, the substrate can beselected according to the function of the resultant element, and can bean ITO glass substrate, a silicon substrate, an Al₂O₃ substrate, or aGaAs substrate.

When the apparatus of the present invention is used, the substrate withor without the bottom electrode layer is fixed on thesubstrate-supporting base in the deposition chamber first. Subsequently,the buffer layer or the electrode layer is formed by a vacuum depositionprocess, for example, a Chemical Vapor Deposition (CVD) process, or aPhysical Vapor Deposition (PVD) process such as evaporation orsputtering. Therefore, the deposition chamber could be a CVD chamber, anevaporation chamber, or a sputtering chamber. Afterwards, a precursorsolution is prepared by considering the size of the droplet sprayed outfrom the atomizer, the property of the solvent, and the volume of thefunctionalized quantum dot. Owing to the functionalized group, thequantum dots can be dispersed in the solvent uniformly. Thereafter, theprecursor solution is sprayed onto the surface of the substrate by theatomizer to form a quantum-dot layer. Moreover, the quantum dot can be ametal quantum dot, a semiconductor quantum dot, a magnetic quantum dot,an organic molecule quantum dot, or a polymer quantum dot. In addition,the diameter of the quantum dot formed by the present invention is lessthan 100 nm, and preferably ranges from several nano-meters to tens ofnano-meters. The dispersion medium of the quantum dots, i.e. thesolvent, can be water, an aqueous solution containing a surfactant, apolar organic solvent such as methanol, a non-polar organic solvent suchas toluene, or a polymer solvent such as a diluted solution of aconjugate polymer, an epoxy resin, polymethylmethacrylate,polycarbonate, or a cyclic olefin co-polymer. The type of the atomizeris not restricted, and can be the conventional atomizer that spraysdroplets by mixing and pressurizing the gas with the solution, or thesupersonic atomizer that produces droplets by using the vibration energyof the piezoelectric ceramics. Besides, the substrate-supporting base ispreferably a rotary plate that can drive the substrate to rotate andheat the substrate. More preferably, the substrate support base canadjust the rotation speed and the temperature of the substrate.Preferably, one shutter is mounted between the substrate supporting baseand the atomizer, and the other shutter is mounted between the substratesupporting base and the evaporation or sputtering source for preventingthe unstable evaporation or sputtering source from depositing on thesubstrate at the beginning of the heating of the evaporation orsputtering source. Similarly, at the initial stage of the spraying ofthe precursor solution, the droplets are not uniform enough. Therefore,the shutter is also used for blocking the non-uniform droplets fromarriving at the substrate.

The preparation of precursor solution is quite important in the presentinvention. In addition to the functionalization that facilitates theuniform dispersion of the quantum dots, the concentration of theprecursor solution should also be calculated precisely. Morespecifically, the concentration of the precursor solution is calculatedfirst in order to produce droplets containing a predetermined number ofquantum dots. Afterwards, a proper amount of quantum-dot powder isdispersed in the solvent to prepare the precursor solution with apredetermined concentration.

For example, the average diameter of the functionalized quantum-dotpowder is 20 nm, and the average diameter of the droplet sprayed fromthe atomizer is 100 nm. If each droplet is predetermined to contain onlyone quantum-dot powder, then the volume concentration of the precursorsolution can be calculated as the following equation (1):

(20 nm)³ /{(100 nm)³+(20 nm)³}=4.63×10⁻³=0.463 V %  (1)

If each droplet is predetermined to contain fifteen quantum-dot powders,then the volume concentration of the precursor solution can becalculated as the following equation (2):

[15×(20 nm)³ ]/[(100 nm)³+15×(20 nm)³]=0.1071=10.71 V %  (2)

If for a pair of droplets, only one contains a quantum-dot particle andthe other does not, then the volume concentration of the precursorsolution will be half the concentration of equation (1).

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 a˜1 c are schematic views showing the formation of thequantum-dot layer by the chemical synthesis of prior art;

FIG. 2 a is an SEM picture showing the distribution of quantum dots inthe quantum-dot layer of prior art;

FIG. 2 b is an SEM picture showing the distribution of quantum dots inthe quantum-dot layer formed by the present invention;

FIG. 3 is a schematic view showing the structure of the light-emittingelement having a ZnSe quantum-dot layer formed by the present invention;

FIG. 4 is a schematic view showing the first preferred embodiment of theapparatus for manufacturing the quantum-dot element of the presentinvention;

FIG. 5 is a schematic view showing the second preferred embodiment ofthe apparatus for manufacturing the quantum-dot element of the presentinvention;

FIG. 6 is a schematic view showing the third preferred embodiment of theapparatus for manufacturing the quantum-dot element of the presentinvention;

FIG. 7 is a schematic view showing the fourth preferred embodiment ofthe apparatus for manufacturing the quantum-dot element of the presentinvention;

FIG. 8 is a schematic view showing the fifth preferred embodiment of theapparatus for manufacturing the quantum-dot element of the presentinvention;

FIG. 9 a is a figure showing the relationship between the brightness andthe voltage of the light-emitting element manufactured by the presentinvention; and

FIG. 9 b is a figure showing the relationship between the brightness andthe voltage of the light-emitting element manufactured by the prior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1Preparation of the Precursor Solution Containing CdSe/ZnS Quantum Dotwith a Diameter of 3 nm

A piezoelectric atomizer that forms toluene droplets with an averagediameter of 1000 nm introduces the precursor solution. If the influenceto the diameter of the droplet caused by the CdSe/ZnS quantum dot isneglected and if each droplet is predetermined to have one quantum-dotparticle, then the volume concentration of the precursor solution can becalculated as the following equation (3):

(3 nm)³/{(1000 nm)³+(3 nm)³}=9.00×10⁻⁹  (3)

If each droplet is predetermined to have three quantum-dot particles,then the desired concentration will be three times the concentrationobtained from equation (3). Similarly, if each pair of droplets has onlyone quantum-dot particle, then the desired concentration will be halfthe concentration obtained from equation (3).

Embodiment 2 Preparation of the Precursor Solution Containing ZnOParticle with a Diameter of 1 μm

The precursor solution is introduced by a conventional atomizer to formwater droplets with an average diameter of 15 μm. If the influence tothe diameter of the droplet caused by the ZnO particle is neglected andif each droplet is predetermined to have one particle, then the volumeconcentration of the precursor solution can be calculated as thefollowing equation (4):

(1 μm)³ /{(15 μm)³+(1 μm)³}=2.96×10⁻⁴  (4)

The volume concentration calculated from equation (4) equals to a weightconcentration of 1.62×10⁻³.

If each droplet is predetermined to have five particles, then thedesired concentration will be five times the concentration obtained fromequation (4). Similarly, if each pair of droplets contains only oneparticle, then the desired concentration will be half the concentrationobtained from equation (4).

Embodiment 3 Preparation of the Precursor Solution Containing SilicaNano-Particle with a Diameter of 20 nm

The precursor solution is introduced by a piezoelectric atomizer to formwater droplets with an average diameter of 100 nm. If the influence tothe diameter of the droplet caused by the silica particle is neglectedand if each droplet is predetermined to have one particle, then thevolume concentration of the precursor solution can be calculated as thefollowing equation (5):

(20 nm)³/{(100 nm)³+(20 nm)³}=4.63×10⁻³=0.463 V %  (5)

If each droplet is predetermined to have fifteen particles, then thedesired concentration will be fifteen times the concentration obtainedfrom equation (5). Similarly, if each pair of droplets contains only oneparticle, then the desired concentration will be half the concentrationobtained from equation (5).

Embodiment 4 Manufacturing of the Light-Emitting Element having ZnSeQuantum Dots

With reference to FIG. 3, there is shown a schematic view of thelight-emitting element having ZnSe quantum dots according to the presentinvention. The light-emitting element includes a glass substrate 110, onwhich an anode layer 120 made of the conductive glass, a hole transportlayer (HTL) 130, an emitting material layer (EML) 140 composed of CdSequantum dots, an electron transport layer (ETL) 150, and a cathode layer170 made of aluminum are formed sequentially. Moreover, there is usuallya LiF layer 160 formed between the cathode layer 170 and the electrontransport layer 150.

In the present embodiment, the EML, the HTL, and the ETL can be made ofany conventional materials, which are listed in the following table:

Light- Material Emitting Green Red Yellow Blue White Small EML Alq{grave over ( )} DPT {grave over ( )} DCM-2 {grave over ( )} RubreneTPAN {grave over ( )} DPAN {grave over ( )} TTBND/ molecule Alq₃ {graveover ( )} Bebq₂ {grave over ( )} TMS-SiPc {grave over ( )} DPAP {graveover ( )} BTX-1 material DMQA {grave over ( )} DCJTB {grave over ( )}Perylene(C₂₀H₁₂) {grave over ( )} Coumarin6 {grave over ( )} ABTX DPVBi{grave over ( )} PPD {grave over ( )} Q {grave over ( )} NMQ {grave over( )} a-NPD₂ {grave over ( )} Quinacrine b-NPD {grave over ( )} TTBND{grave over ( )} DCTA {grave over ( )} TDAPTz HTL TPAC {grave over ( )}TPD {grave over ( )} a-NPD {grave over ( )} 2Me-TPD {grave over ( )}FTPD {grave over ( )} Spiro-TPD(TAD) {grave over ( )} t-TNATA {graveover ( )} OTPAC {grave over ( )} CuPc {grave over ( )} TPTE {grave over( )} m-MTDATA ETL Alq₃ {grave over ( )} Bebq₂ {grave over ( )} BND{grave over ( )} OXD {grave over ( )} ZnPBT {grave over ( )} PBD {graveover ( )} TAZ Polymer EML PPV {grave over ( )} PF {grave over ( )}MEH-PPV material HTL PEDOT {grave over ( )} PAni {grave over ( )} PVK{grave over ( )} PTPDES

Wherein the above abbreviations are defined as follows:

NPB:

-   N,N′-di(naphthalen-1-yl)-N,N′-di(phenyl)benzidin,

α-NPB:

-   N,N′-Bis(naphthalen-1-yl)-N,N′-bis(phenyl)benzidine,

DMFL-NPB:

-   N,N′-di(naphthalen-1-yl)-N,N′-di(phenyl)-9,9-dimethyl-fluorene,

TPD:

-   N,N′-Bis-(3-methylphenyl)-N,N′-bis-(phenyl)-benzidine,

Spiro-TPD:

-   N,N′-bis-(3-methylphenyl)-N,N′-bis-(phenyl)-spiro,

DMFL-TPD:

-   N,N′-bis(3-methylphenyll)-N,N′-bis(phenyl)-9,9-diphenyl-fluorene,

Spiro-NPB:

-   N,N′-di(naphthalen-1-yl)-N,N′-diphenyl-spiro),

TCP:

-   1,3,5-tris(carbazol-9-yl)-benzene,

TNB:

-   N,N,N′,N′-tetrakis(naphth-1-yl)-benzidine,

MCP:

-   1,3-bis(carbazol-9-yl)-benzene,

PVK:

-   poly (N-vinyl carbazole),

PEDOT:

-   poly (ethylenedioxythiophene,

PSS:

-   poly (styrene sulfonic acid),

MEH-PPV:

-   Poly(2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene),

MEH-BP-PPV:

-   Poly[2-Methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene    -co-4,4′-bisphenylenevinylene],

PF-BV-MEH:

-   Poly[(9,9-dioctylfluoren-2,7-diyl)-co-(1,4-diphenylene-vinylene-2-methoxy-5-{2-ethylhexyloxy    }benzene)],

PF-DMOP:

-   Poly[(9,9-dioctylfluoren-2,7-diyl)-co-(2,5-dimethoxybenzen-1,4-diyl)],

PFH:

-   Poly[(9,9-dihexylfluoren-2,7-diyl)-alt-co-(benzen-1,4-diyl)],

PFH-EC:

-   Poly[(9,9-dihexylfluoren-2,7-diyl)-co-(9-ethylcarbazol-2,7-diyl)],

PFH-MEH:

-   Poly[(9,9-dihexylfluoren-2,7-diyl)-alt-co-(2-methoxy-5-{2-ethylhexyloxy}phenylen-1,4-diyl)],

PFO:

-   Poly[(9,9-dioctylfluoren-2,7-diyl),

PF-PPV:

-   Poly[(9,9-di-n-octylfluoren-2,7-diyl)-co-(1,4-vinylenephenylene)],

PF-PH:

-   Poly[(9,9-dihexylfluoren-2,7-diyl)-alt-co-(benzen-1,4-diyl)],

PF-SP:

-   Poly[(9,9-dihexylfluoren-2,7-diyl)-alt-co-(9,9′-spirobifluoren-2,7-diyl)],

Poly-TPD:

-   Poly(N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl)benzidine,

Poly-TPD-POSS:

-   Poly(N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl)benzidine,

TAB-PFH:

-   Poly[(9,9-dihexylfluoren-2,7-diyl)-co-(N,N′-di(4-butylphenyl)-N,N′-diphenyl-4,4′-diyl-1,4-diaminobenzene)],

PPB:

-   N,N′-Bis(phenanthren-9-yl)-N,N′-diphenylbenzidine,

Alq₃:

-   Tris-(8-hydroxyquinoline)aluminum,

BAlq₃:

-   (Bis-(2-methyl-8-quinolinolate)-4-(phenylphenolato)-alumium),

BCP:

-   2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline,

CBP:

-   4,4′-Bis(carbazol-9-yl)biphenyl,

TAZ:

-   3-(4-Biphenylyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole

In the present embodiment, the apparatus for manufacturing thequantum-dot element is shown in FIG. 4. An evaporation chamber 200having a plurality of evaporation sources 210 is used to deposit thehole transport layer, the quantum-dot emitting layer, and the electrontransport layer successively on the substrate 110. Asubstrate-supporting base 220 is located in the evaporation chamber 200for fixing the substrate 110. In addition, an atomizer 230 is used topressurize the mixture of a gas and a solution More specifically,nitrogen and a toluene solution containing functionalized CdSe quantumdots are sprayed into the evaporation chamber 200 for generatingdroplets containing quantum dots. The nitrogen and the toluene solutionare fed respectively through a gas inlet 231 and a sample inlet 232,both of which are connected with the atomizer 230. Furthermore, severalshutters 240 are mounted between the substrate-supporting base and theatomizer 230, as well as between the substrate supporting base and theevaporation sources 210. Owing to the shutters 240, the atomizer 230 andthe evaporation sources 210 can be switched and prevented fromcontaminating with each other. Preferably, a sieve 250 is mountedbetween the atomizer 230 and the shutter 240 for controlling the size ofdroplets that deposit on the substrate 110. Besides, the atomizer 230 isdisposed at the bottom of the chamber 200, and the substrate-supportingbase 220 is located at the top of the chamber 200. Hence, the dropletstransported upwardly can deposit uniformly on the substrate and form aquantum-dot layer with uniform distribution of quantum dots.

The substrate-supporting base 220 is a rotary plate that drives thesubstrate to rotate. Also, the substrate-supporting base 220 can heatthe substrate so as to increase the uniformity of the hole transportlayer and electron transport layer formed by evaporation, as well as thequantum-dot emitting layer formed by atomization. In addition, thesolvent on the substrate can be driven out accordingly. The evaporatedmaterial includes an organic molecule, an organic metal, an organicsemiconductor, a metal, a semiconductor, a hole or electron transportmaterial, and a super conductive material. In particular, the organicmolecule contains the small organic molecule that has a molecular weightless than 100,000, and an organic polymer. The organic metal is amolecule having metal and an organic group such as C—R, O—R, N—R, or S—Rgroup, wherein R represents an organic molecule. The organicsemiconductor contains an organic compound that has an electricallyconductive property and a light-emitting property, such as a conjugatepolymer. The metal includes groups 1A, 2A, 3A, 4A, 5A, 6A, 7A, 8A, 1B,and 2B metals in the periodic table. The semiconductor contains thesemiconductors of groups 4B and the compound semiconductors of groups1B, 2B, 3B, 4B, 5B, 6B, and 7B. The hole or electron transport materialincludes the hole or electron transport materials used for the PLED andOLED. As for the super conductive material, it includes the compoundsthat have at least two of Y, Ba, Cu, and O elements and othersuperconductors.

When the quantum-dot element is manufactured, the substrate 110 havingthe anode layer 120 made of the conductive glass is transferred into theevaporation chamber 200 and fixed on the substrate-supporting base 220first. Simultaneously, the evaporation source 210 is turned on undervacuum condition to form a hole transport layer 130 on the substrate110. Afterwards, a high-pressure gas is used to spray out the dropletscontaining functionalized quantum dots through the atomizer 230.Subsequently, the evaporation source 210 of the electron transport layer150 is turned on to form the electron transport layer 150 on the glasssubstrate 110. Finally, the glass substrate 110 is transferred out ofthe chamber, and then sent to other apparatus for depositing the cathodelayer 170. At this point, the manufacture of the light-emitting elementis finished. The distribution of quantum dots in the quantum-dotemitting layer 140 can be as shown as FIG. 2 b.

The atomizer 230, the gas inlet 231, and the sample inlet 232 aremounted inside the chamber 200 in the present embodiment. Also, thoseparts can be mounted outside of the chamber 200 except the spray head ofthe atomizer 230, as shown in FIG. 5. In this preferred embodiment, thecrucible is used to serve as the evaporation source, which is melted bythe thermal resistance materials such as a tungsten line or a tantalumline. However, the deposition chamber 300 can also use an electron-beamgun 310 to melt the evaporation source, and an externally connectedremovable atomizer 330 to deposit a thin film on the substrate 320, asshown in FIG. 6. Alternatively, with reference to FIG. 7, the laser 410can be used to gasify the target 420 in the chamber 400, and the gas 430can transfer the gasified target material to form the electrode layer orthe buffer layer on the substrate 450. Also, a removable atomizer 440 isexternally connected to form the quantum-dot layer on the substrate 450.Furthermore, in the quartz tube 530 of the chamber 500, a film is formedon the substrate 520 by the Chemical Vapor Deposition process, as shownin FIG. 8. More particularly, the feed inlet 510 is located at one endof the quartz tube 530, and at the other end of the quartz tube 530,there is an outlet 540 connecting with a pump. The outlet 540 cangenerate a pressure difference in the quartz tube 530. Thus, thepressure difference drives the gas to flow and form a film on thesubstrate 520. Similarly, the atomizer 550 serves to form the quantumdots in the film.

In the present invention, the carrier transport layer can be depositedoptionally before or after the quantum-dot layer is formed.Alternatively, the carrier transport layer and the quantum-dot layer canbe formed by turns. Finally, the electrode can also be deposited in thesame chamber. As the above-mentioned steps are all carried out in thevacuum chamber, they can be accomplished in a continuous process.Consequently, the manufacturing time and cost are reduced. Besides, theproduct is effectively prevented from being contaminated, Moreover, thequantum dots can be distributed uniformly on the substrate due to thespraying of the atomizer, The size of the quantum dots can be reduced tonano-meter level successfully.

The relationship between the brightness and the exerted voltage of theemitting element having ZnSe quantum dots formed by the presentinvention is compared with that of the conventional emitting element, ofwhich the quantum-dot layer is formed by coating. As shown in FIG. 9 a,the brightness of the emitting element manufactured by the presentinvention reaches 10,000 lumens as the voltage is 9V. However, thebrightness of the conventional emitting element is less than 1,000lumens as the voltage is 9V, as shown in FIG. 9 b. Therefore, theemitting element manufactured by the apparatus of the present inventionexhibits a substantially improved light-emitting efficiency.

The above detailed descriptions are given by way of example and notintended to limit the invention solely to the embodiments describedherein.

1-14. (canceled)
 15. A method of forming a quantum-dot particles layeron a substrate, comprising: (A) preparing a precursor solutioncontaining quantum-dot particles by dissolving quantum-dot particles ina solvent, and providing an apparatus comprising a reaction chamber; asubstrate supporting base; and at least one atomizer, wherein thesubstrate supporting base locates inside the reaction chamber for fixingthe substrate, the atomizer connects to the reaction chamber or locatesinside the reaction chamber, the atomizer has a gas inlet and a sampleinlet, the atomizer can pressurize a mixture of a gas and a solution,and the volume concentration of the precursor solution is calculated asthe following equation:[X ³/(Y ³ +X ³)]×n=volume concentration of the precursor solution,wherein X is a diameter of the quantum-dot particle; Y is apredetermined diameter of a droplet; and n is a number of thequantum-dot particles contained in each of the droplet; (B) locating asubstrate on the supporting base; (C) feeding the gas inlet and thesample inlet of the atomizer; respectively with a gas and the precursorsolution prepared in the step (A); and (D) generating dropletscontaining quantum-dot particles and spraying the generated droplets tothe surface of the substrate by the atomizer.
 16. The method of forminga quantum-dot particles layer on a substrate according to claim 15,further comprising a step (E): heating the substrate having dropletsthereon to dry the substrate after step (D).
 17. The method of forming aquantum-dot particles layer on a substrate according to claim 15,wherein the solvent of step (A) is selected from the group consisting ofwater, an aqueous solution containing a surfactant, a polar organicsolvent, a non-polar organic solvent, and a polymer solvent.
 18. Themethod of forming a quantum-dot particles layer on a substrate accordingto claim 15, wherein the quantum-dot particle is selected from a groupconsisting of a metal quantum-dot particle, a semiconductor quantum-dotparticle, a magnetic quantum-dot particle, a small organic moleculequantum-dot particle, and a polymer quantum-dot particle.
 19. The methodof forming a quantum-dot particles layer on a substrate according toclaim 15, wherein the gas of step (C) is an inert gas or nitrogen gas.20. The method of forming a quantum-dot particle layer on a substrateaccording to claim 15, further comprising sieving the generated dropletsfor a predetermined diameter by a sieve after generating dropletscontaining quantum-dot particles.
 21. The method of forming aquantum-dot particles layer on a substrate according to claim 15,wherein the diameter of the droplet (Y) is 10 nm to 1×10⁴ nm.
 22. Themethod of forming a quantum-dot particles layer on a substrate accordingto claim 15, wherein the diameter of the quantum-dot particle (X) is 0.1nm to 100 nm.
 23. The method of forming a quantum-dot particles layer ona substrate according to claim 15, wherein the number of the quantum-dotparticles contained in each of the droplet (n) is 1 to 100.